Korean J Radiol.  2012 Jun;13(3):275-282. 10.3348/kjr.2012.13.3.275.

Thyroid Incidentaloma Detected by Time-Resolved Magnetic Resonance Angiography at 3T: Prevalence and Clinical Significance

• Choi N
• Moon WJ
• Kim HY
• Roh HG
• Choi JW

• KMID: 1372846
• DOI: http://doi.org/10.3348/kjr.2012.13.3.275

Abstract

OBJECTIVE
To determine the prevalence of thyroid incidentalomas detected by time-resolved magnetic resonance angiography (TRMRA) and to evaluate their clinical significance by using an ultrasonographic (US) and cytologic correlation.
MATERIALS AND METHODS
We retrospectively reviewed 2010 consecutive TRMRA examinations performed at our institution between August 2006 and April 2010. The TRMRA findings of thyroid incidentalomas were analyzed according to location, size, as well as vascularity, and were correlated with the US findings and cytologic results. Each nodule was classified as suspiciously malignant, indeterminate or probably benign according to the US criteria recommended by the Korean Society of Thyroid Radiology.
RESULTS
A total of 102 incidentalomas were detected in 90 of 2010 patients (5%). TRMRA showed homogenous hypervascularity in 48 (47%), inhomogeneous hypervascularity in 46 (45%), and hypovascularity in 8 (8%) thyroid nodules. At follow-up study, out of 26 patients with 30 incidentalomas on TRMRA, 27 nodules were identified on US. Of the 27 nodules, 24 (89%) nodule were classified as indeterminate, two (7%) as probably benign, and one (4%) as suspiciously malignant. Among the 16 nodules with available cytopathologic results, 14 (82%) were benign, one (6%) was indeterminate, and one (6%) was malignant.
CONCLUSION
Thyroid incidentalomas are found in 5% of TRMRA examinations. Although their presence does not necessarily indicate malignancy, nonspecific findings of detected incidentalomas on TRMRA require further evaluation by US.

Keyword

Magnetic resonance angiography; ime-resolved; Ultrasonography; Thyroid; Neoplasm; Incidentaloma

MeSH Terms

Adult
Aged
Aged, 80 and over
Contrast Media/diagnostic use
Female
Humans
Incidental Findings
Magnetic Resonance Angiography/*methods
Male
Middle Aged
Organometallic Compounds/diagnostic use
Prevalence
Retrospective Studies
Thyroid Neoplasms/*diagnosis/epidemiology/ultrasonography
Thyroid Nodule/*diagnosis/epidemiology/ultrasonography

Figure

• 

  Fig. 1 58-year-old man with left thyroid nodule, subsequently diagnosed as benign by US-guided FNAB. A. Coronal MIP image of TRMRA shows left thyroid nodule with homogenous hypervascularity. B. Transverse US image of left thyroid reveals smooth, oval, isoechoic, solid nodule, classified as indeterminate. FNAB = fine needle aspiration biopsy, MIP = maximum intensity projections, TRMRA = time-resolved MR angiography, US = ultrasonographic

• 

  Fig. 2 60-year-old man with left thyroid nodule, subsequently diagnosed as benign by US-guided FNAB. A. Coronal MIP image of TRMRA shows left thyroid nodule with inhomogenous hypervascularity (black lined arrows). B. Longitudinal US image of left thyroid reveals smooth, oval, isoechoic predominantly cystic nodule, classified as indeterminate. Internal hypervascular areas (black lined arrows on A) correlate with isoechoic solid portion (arrows). MIP = maximum intensity projections, TRMRA = time-resolved MR angiography, US = ultrasonographic

• 

  Fig. 3 66-year-old man with right thyroid nodule. A. Coronal MIP image of TRMRA shows right thyroid nodule (black lined arrows) with hypovascularity. B. Longitudinal US image of right thyroid reveals smooth, oval, isoechoic, predominantly cystic nodule with comet tail artifacts (arrows), which is probably classified as benign nodule. MIP = maximum intensity projections, TRMRA = time-resolved MR angiography, US = ultrasonographic

• 

  Fig. 4 49-year-old woman with left papillary thyroid carcinoma. A. Coronal MIP image of TRMRA shows left thyroid nodule (black lined arrow) with homogenous hypovascularity. B. Transverse US image of left thyroid shows spiculated, round, hypoechoic, solid nodule, classified as suspicious. MIP = maximum intensity projections, TRMRA = time-resolved MR angiography, US = ultrasonographic

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  Fig. 5 Graph shows dynamic enhancement curves for nonmalignant and malignant nodules. Mean signal intensity of 16 nonmalignant nodules on same temporal images was used to create time-to-signal intensity curve for nonmalignant nodules.

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